The Democrats' historic handoff to Clinton arrived with affection from one ex-president and an endorsement from an outgoing one. But also came with a warning: That last glass ceiling isn't shattered yet and the Republican nominee is a formidable and unpredictable foe.

Clinton formally captured the Democratic nomination Tuesday night and declared the barrier keeping women from the presidency nearly broken. Her husband, former President Bill Clinton offered a personal testimonial, and President Barack Obama was on deck to make the case for electing his former secretary of state.

But Wednesday morning, Clinton's rival touched off a firestorm with his call for Russia to launch a cyberattack onClinton's emails.

Obama and other Democrats elicited Trump's startling remarks by suggesting the Russian government was behind the hack of Democratic National Committee emails that toppled the party's chief earlier this week. In an NBC News interview, Obama suggested that Russian President Vladimir Putin was actually rooting for Trump — although he provided no evidence — and said the GOP businessman has "expressed admiration" for Putin.

Trump declared Wednesday he has "nothing to do with Russia," but quickly went much further.

"Russia, if you're listening, I hope you're able to find the 30,000 e-mails that are missing," Trump said, in an apparent reference to Clinton's State Department emails. "I think you will probably be rewarded mightily by our press. Let's see if that happens. That'll be next."

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The suggestion appeared to be an off-the-cuff riff. Still, the candidate repeated it in a follow-up tweet. It drew swift condemnation from the Clinton campaign.

"This has to be the first time that a major presidential candidate has actively encouraged a foreign power to conduct espionage against his political opponent," said Clinton adviser Jake Sullivan. "That's not hyperbole, those are just the facts. This has gone from being a matter of curiosity, and a matter of politics, to being a national security issue."

Backers of vanquished liberal Bernie Sanders considered walking out on a Kaine's speech, a sign of residual frustration with Clinton, the party and the perception, fueled by the leaked emails, that top officials had greased her path to victory.

Despite the swirl of distractions, Democrats appeared to be finding unity as they formally sealed the deal behindClinton on Tuesday night. A convention that had been consumed by drama of formally defeating Sanders had turned to showcasing the coalition Clinton will need to win — blacks, Hispanics, women and young people.

The base-boosting strategy has some Democrats worried Clinton is ceding too much ground to her opponent. Her convention has made little mention of the economic insecurity and anxiety that has, in part, fueled Trump's rise with white, working-class voters. Trump has cast himself as the "law-and-order" candidate and promised to get tough on terrorists. Democrats have rarely noted the threat of terrorism or the Islamic State group.

Speaking on MSNBC Wednesday morning, Biden said his party has failed to connect with and show "respect" for white, working-class voters.

Trump accused Democrats of avoiding talking about the Islamic State group "because they grew it." In his news conference, he hammered Clinton on her trade policy, saying if she is elected she will flip her opposition to the Trans-Pacific trade deal. He also backed an increase to the minimum wage to $10 per hour.

During the Democrats' convention, the fallout from the hack and the effort to appease Sanders' fans competed with the celebration of Clinton's landmark achievement. But Tuesday night's roll call vote sealed her nomination and Sanders himself stepped up in the name of unity to ask that her nomination be approved by acclamation.

The unhappiest among his followers filed out, occupied a media tent and staged a sit-in, some with tape on their mouths to signify their silencing by the party. But a teary Sanders acknowledged the end. Obama was "kind enough to call," he said Wednesday in a meeting with New England delegates. "As of yesterday, I guess, officially our campaign ended."

The roll call vote was laden with emotion and symbols of women's long struggle to break through political barriers. Holding a sign saying "Centenarian for Hillary," 102-year-old Jerry Emmett of Prescott, Arizona, cast her state delegation's vote. She was born before women won the right to vote in 1920, and remembered her mother casting a ballot for the first time.

Said Clinton, in a surprise appearance on video at night's end: "We just put the biggest crack in that glass ceiling yet." The crowd roared.

Bill Clinton traced the couple's love story chapter and verse, starting from their meeting in a library and proceeding through his head-strong courtship and on through the years. Unsavory episodes, like his numerous dalliances with women in Arkansas and the nearly career-ending liaison with White House intern Monica Lewinsky, were omitted.